Ornamental design for a coffee table



FIG. 1 is a perspective view of the coffee table showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a side elevational view (taken from the right side) thereof;

FIG. 4 is a top plan view thereof; and,

FIG. 5 is a bottom plan view thereof. 

The ornamental design for a coffee table, as shown and described. 